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Maxim Defense MDX 505 PDX Upper Kit w/ Brace - Arid


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Born from the SOCOM PDW solicitation, the NEW Maxim Defense PDX™ U.R.G. is designed to handle the fierce demands of the Tier 1 community. The PDX™ U.R.G. dominates in close quarter encounters and achieves maximum energy on target without sacrificing accuracy at distance. At just 14” in overall length, the PDX™ U.R.G. is the ultimate choice for when concealment and personal defense is non-negotiable.


At the heart of the PDX™ KIT is their newly developed Maxim SCW™ brace system. This patent-pending design cuts down the length of the brace to 4” and offers an integrated BCG with interchangeable buffer weights to give you the flexibility to maximize performance and versatility without sacrificing functionality or form. 


The PDX™ KIT is also equipped with Maxim’s HATEBRAKE™ Muzzle Booster. This patent-pending device significantly reduces recoil, decreases the flash signature, pushes gasses and concussion waves downrange away from the operator improving overall execution. The PDX Kit uses a Direct Impingement system.

The PDX Kit comes with everything you need to turn your lower receiver into a Maxim Defense PDX.



  • HATEBRAKE installed under handguard
  • MOA accurate
  • M-slot compatible handguard
  • Military grade materials [6Al-4V Titanium, 17-4 Stainless Steel, 7075 and 6061 Aluminum]
  • SCW Buffer-carrier
  • HK height rail for a more rigid upper receiver
  • Military tested Rapid Deploying PDW Brace



  • Optimized Personal Defense Weapon kit
  • Increased reliability due to included HATEBRAKE
  • Optimized low flash and sound signatures
  • Designed to be installed on any Mil-Spec lower receiver



  • Weight: 5 lbs
  • Length: 18 inch upper (collapsed)
  • Barrel Length: 5.5 inches
  • Caliber:5.56, 7.62×39, .300BLK
  • Muzzle Velocity: 5.56 – 1,965 fps avg (62 gr) / 7.62×39 – 1675 fps avg (124 gr)
  • Muzzle Threads: 1/2x28 / 5/8x24
  • Finish: Arid
More Information
Product Type Stock
Manufacturer Maxim Defense

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